Isolation And Identification Of The Pathogens Of Leaf Spot Diseases Of Several Mangroves In Leizhou Peninsula And Biological Characteristics Of Corynespora Cassiicola Caused Leaf Spot Of Acanthus Ilicifolius

Mangrove is a kind of special woody plant community which can be amphibious in tropical and subtropical coastal area.It has high value of pharmaceutical and ecology.In recent years,mangrove diseases have become more and more serious due to the changes in environment and ecology,and some have threatened the healthy growth of mangroves.In order to study the epidemic situation of mangrove plant diseases in recent years,the investigation for mangrove plant diseases of Leizhou Peninsula were conducted and the pathogens of new diseases of several mangroves were isolated and identified.Moreover,the biological characteristics of the pathogen which caused leaf spot disease of Acanthus ilicifolius were studied in this paper.(1)In 2019,mangrove plant diseases were investigated in the east island of Leizhou Peninsula,Kuzhu Bridge and Gaoqiao mangrove region,and four new diseases were found on leaves of Acanthus ilicifolius,Sonneratia apetala,Acrostichum aureum and Excoecaria agallocha.All of them occurred sporadically.(2)Using PDA as the medium,the pathogens of the four new diseases were isolated by the method of pathogen-containing tissue isolation.According to the morphological characteristics and the gene sequence analysis of ITS,TUB2,GAPDH,CHS-1,ACT,TEF-1?,the pathogens causing leaf spot disease of Acanthus ilicifolius,Sonneratia apetala,Acrostichum aureum and Excoecaria agallocha,were identified as Corynespora cassiicola,Colletotrichum siamense,Nigrospora lacticolonia,and Lasiodiplodia theobromae,respectively.(3)The results of the biological characteristics of strain ALY1 isolated from the leaf spot of Acanthus ilicifolius showed that the optimum grown was VB2.The temperature range of mycelium growth is 10??35?,and the optimum growth temperature is 25?? 28?;the mycelium can grow in the range of p H3.0?p H12.0,and the optimum growth temperature is p H6.0? p H7.0;the effect of light on the growth of mycelium was not obvious;the mycelium can grow in the range of 4%?8% salt concentration.